Curable coating compositions containing blends of carbamate-functional compounds

ABSTRACT

The present invention provides a curable coating composition that includes at least three components. The coating composition includes a component (a) that includes one or both of a compound (a)(1) having at least one carbamate group or terminal urea group according to the invention and having at least two linking groups that are urethane or urea or a compound (a)(2) having at least two groups selected from carbamate groups, terminal urea groups, or combinations of the two and at least four urethane or urea linking groups. The second component (b) of the coating composition includes a polymer resin comprising active hydrogen-containing functional groups reactive with the third component (c). The resins is selected from polyester, polyurethane, or polyester-polyurethane copolymers Component (c) of the coating composition is a curing agent that is reactive with the first two components. Preparation of coated articles using the compositions of the invention is also disclosed.

The present application is a continuation-in-part of Green et al, U.S.application Ser. No. 08/997,317, filed Dec. 23, 1997 now U.S. Pat. No.5,994,479, which is continuation-in-part of each of the following: Greenet al., U.S. application Ser. No. 08/886,321, filed Jul. 1, 1997 nowU.S. Pat. No. 5,872,195, which is a continuation of provisionalapplication No. 60/021,068, filed Jul. 1, 1996; McGee et al., and a CIPof U.S. application Ser. No. 08/698,529, filed Aug. 15, 1996 now U.S.Pat. No. 5,854,385, which is a continuation of Ser. No. 08/540,274,filed Oct. 6, 1995, now abandoned; Menovcik et al., and a CON U.S.application Ser. No. 08/333,917, filed Nov. 3, 1994, now U.S. Pat. No.5,744,550, issued Apr. 28, 1998; U.S. application Ser. No. 08/176,608,filed Jan. 3, 1994, now abandoned; Rehfuss et al., U.S. application Ser.No. 08/287,351, filed Aug. 8, 1994 now abandoned, which is acontinuation-in-part of Ser. No. 08/098,177, filed Jul. 28, 1993, nowabandoned; McGee et al., U.S. application Ser. No. 08/867,547, filedJun. 2, 1997 now U.S. Pat. No. 6,040,062, issued Mar. 21, 2000; which isa continuation of U.S. application Ser. No. 08/513,587, filed Aug. 10,1995, now U.S. Pat. No. 5,726,244, issued Mar. 10, 1998; Menovcik etal., U.S. application Ser. No. 08/547,513, filed Oct. 24, 1995, now U.S.Pat. No. 5,726,274, issued Mar. 10, 1998, which is a division of U.S.application Ser. No. 08/361,344, filed Dec. 21, 1994, now abandoned;Menovcik et al., U.S. application Ser. No. 08/547,174, filed Oct. 24,1995, now U.S. Pat. No. 5,723,552, issued Mar. 3, 1998, which is adivisional of U.S. application Ser. No. 08/361,344, filed Dec. 21, 1994,now abandoned; Menovcik et al., U.S. application Ser. No. 08/698,524,filed Aug. 15, 1996, now U.S. Pat. No. 5,792,810, issued Aug. 11, 1998,which is a continuation of Ser. No. 08/550,880, filed Oct. 6, 1995 nowabandoned; Bammel et al., U.S. application Ser. No. 08/698,526, filedAug. 15, 1996, now U.S. Pat. No. 5,760,127, issued Jun. 2, 1998, whichis a continuation of U.S. application Ser. No. 08/686,929, filed Oct. 6,1995 now abandoned; Ohrbom et al., U.S. application Ser. No. 08/667,261,filed Jun. 20, 1996, now U.S. Pat. No. 5,777,048; issued Jul. 7, 1998;Ohrbom et al., U.S. application Ser. No. 08/698,528, filed Aug. 15,1996, now U.S. Pat. No. 5,756,213, issued May 26, 1998, which is acontinuation of U.S. application Ser. No. 08/540,275, filed Oct. 6,1995, now abandoned; Ohrbom et al., U.S. application Ser. No.08/698,522, filed Aug. 15, 1996 now U.S. Pat. No. 5,827,930, which is acontinuation of U.S. application Ser. No. 08/540,277, filed Oct. 6,1995, now abandoned; McGee et al., U.S. application Ser. No. 08/698,523,filed Aug. 15, 1996, now U.S. Pat. No. 5,770,650, issued Jun. 23, 1998,which is a continuation of U.S. application Ser. No. 08/540,279, filedOct. 6, 1995, now abandoned; Green et al., U.S. application Ser. No.08/886,321, filed Jul. 1, 1997 now U.S. Pat. No. 5,872,195, which is acontinuation of provisional application 60/021,068, filed Jul. 1, 1996;Bammel et al., U.S. application Ser. No. 08/831,810, filed April 2, 1997now pending; Ohrbom et al, U.S. application Ser. No. 08/333,804, filedNov. 3, 1994 now pending.

FIELD OF THE INVENTION

This invention concerns curable coating compositions, especiallycompositions for high-gloss topcoats, particularly for clearcoats ofcolor-plus-clear composite coatings.

BACKGROUND OF THE INVENTION

Curable, or thermosettable, coating compositions are widely used in thecoatings art, particularly for topcoats in the automotive and industrialcoatings industry. Color-plus-clear composite coatings are particularlyuseful as topcoats for which exceptional gloss, depth of color,distinctness of image, or special metallic effects are desired. Theautomotive industry has made extensive use of these coatings forautomotive body panels.

Single-layer topcoats and the clearcoats of color-plus-clear compositecoatings, however, require an extremely high degree of clarity and glossto achieve the desired visual effect. Such coatings also require a lowdegree of visual aberrations at the surface of the coating in order toachieve the desired visual effect such as high distinctness of image(DOI). As such, these coatings are especially susceptible to aphenomenon known as environmental etch. Environmental etch manifestsitself as spots or marks on or in the finish of the coating that oftencannot be rubbed out. It is often difficult to predict the degree ofresistance to environmental etch that a high gloss topcoat orcolor-plus-clear composite coating will exhibit. Many coatingcompositions known for their durability and/or weatherability when usedin exterior paints, such as known high-solids enamels, do not providethe desired level of resistance to environmental etch when used in highgloss coatings such as the clearcoat of a color-plus-clear compositecoating.

Various compositions have been proposed to meet the above requirementsfor use as the topcoat coating or as the clearcoat of a color-plus-clearcomposite coating, including polyurethanes, acid-epoxy systems and thelike. However, many prior art systems suffer from disadvantages such ascoatability problems, marginal compatibility with the pigmentedbasecoat, solubility problems, and marginal appearance. Moreover, whileone-pack compositions are preferred to two-pack compositions (in whichthe reactive component must be separated before application to preventpremature reaction), very few one-pack coating compositions have beenfound that provide satisfactory resistance to environmental etch,especially in the demanding environment of automotive coatings.

In addition, it is desirable to provide coatings with a good combinationof properties such as durability, hardness, flexibility, and resistanceto scratching, marring, solvents, and acids.

Curable coating compositions utilizing carbamate-functional resins aredescribed, for example, in U.S. Pat. Nos. 5,693,724, 5,693,723,5,639,828, 5,512,639, 5,508,379, 5,451,656, 5,356,669, 5,336,566, and5,532,061, and U.S. application Ser. Nos. 08/886,321, filed Jul. 1,1997, 08/698,529, filed Aug. 15, 1996, 08/719,670, filed Sep. 25, 1996,08/166,277, filed Dec. 13, 1993, 08/339,999, filed Nov. 15, 1994,08/333,917, filed Nov. 3, 1994, 08/176,608, filed Jan. 3, 1994,08/287,351, filed Aug. 8, 1994, 08/804,239, filed Feb. 20, 1997,08/333,804, filed Nov. 3, 1994, 08/884,613, filed Jun. 30, 1997,08/885,638, filed Jun. 30, 1997, 08/513,587, filed Aug. 10, 1995,08/867,547, filed Jun. 2, 1997, 08/547,514, filed Oct. 24, 1994,08/547,513, filed Oct. 24, 1994, 08/547,174, filed Oct. 24, 1994,08/698,524, filed Aug. 15, 1996, 08/698,526, filed Aug. 15, 1996,08/667,261, filed Jun. 20, 1996, 08/698,528, filed Aug. 15, 1996,08/698,522, filed Aug. 15, 1996, 08/698,572, filed Aug. 15, 1996,08/698,523, filed Aug. 15, 1996, 08/673,935, filed Jul. 1, 1996,08/886,321, filed Jul. 1, 1997, and 08/831,810, filed Apr. 2, 1997, eachof which is incorporated herein by reference. These coating compositionscan provide significant etch advantages over other coating compositions,such as hydroxy-functional acrylic/melamine coating compositions. It mayoften be desirable, however, to provide still further improvements inthe above-described coating properties.

SUMMARY OF THE INVENTION

The present invention provides a curable coating composition thatincludes at least three components: a component (a), a component (b),and a component (c).

Component (a) includes one or both of two compounds, compounds (a)(1)and (a)(2) having at least one carbamate group or terminal urea group.When used in connection with the invention, the term "carbamate group"refers to a group having a structure: ##STR1## in which R is H or alkyl.Preferably, R is H or alkyl of from 1 to about 4 carbon atoms, and morepreferably R is H. When used in connection with the invention, "terminalurea group" refers to a group having a structure: ##STR2## in which R'and R" are each independently H or alkyl, or R' and R" together form aheterocyclic ring structure. Preferably, R' and R" are eachindependently H or alkyl of from 1 to about 4 carbon atoms or togetherform an ethylene bridge, and more preferably R' and R" are eachindependently H. The terminal urea group of the invention isdistinguished from urea linking groups for which R" would be other thanalkyl.

Compound (a)(1) has at least one carbamate group or terminal urea groupand at least two linking groups that are urethane or urea. Preferredcompounds (a)(1) may be represented by any of the structures: ##STR3##in which R, R', and R" are as previously defined; R¹ is alkylene orarylalkylene, preferably alkylene, and particularly alkylene of 5 to 10carbon atoms; R² is alkylene or substituted alkylene, preferably havingfrom about 2 to about 4 carbon atoms; R³ is alkylene (includingcycloalkylene), alkylarylene, arylene, or a structure that includes acyanuric ring, a urethane group, a urea group, a carbodiimide group, abiuret structure, or an allophonate group, preferably alkylene(including cycloalkylene) or a structure that includes a cyanuric ring;n is from 0 to about 10, preferably from 0 to about 5; m is from 2 toabout 6, preferably 2 or 3; and L is O, NH, or NR⁴, where R⁴ is analkyl, preferably an alkyl of 1 to about 6 carbon atoms; p is from 1 to5, preferably 1 or 2, and m+p is 2 to 6, preferably about 3. Preferably,R³ is alkylene (including cycloalkylene), alkylarylene, arylene, or astructure that includes a cyanuric ring.

The compound (a)(1) may be prepared by a process having a step ofreacting together a monomeric polyisocyanate (a)(1)(B) and a compound(a)(1)(A) having a carbamate or terminal urea group or a group that canbe converted to a carbamate or terminal urea group and also having agroup that is reactive with isocyanate functionality. In the case of agroup that can be converted to carbamate or urea, the conversion to thecarbamate or terminal urea group is carried out either at the same timeas the reaction involving the polyisocyanate or afterwards to form thecompound (a)(1) of the first component.

Alternatively or in addition to this compound (a)(1), the component (a)may include a compound (a)(2) having at least two groups selected fromcarbamate groups, terminal urea groups, or combinations of the two andat least four urethane or urea linking groups. Preferred compounds(a)(2) may be represented by any of the structures: ##STR4## in which R,R', and R" are as previously defined; R¹ is alkylene or arylalkylene,preferably alkylene, and particularly alkylene of 5 to 10 carbon atoms;R² is alkylene or substituted alkylene, preferably having from about 2to about 4 carbon atoms; R³ is alkylene (including cycloalkylene),alkylarylene, arylene, or a structure that includes a cyanuric ring, aurethane group, a urea group, a carbodiimide group, a biuret structure,or an allophonate group, preferably alkylene (including cycloalkylene)or a structure that includes a cyanuric ring; n is from 0 to about 10,preferably from 0 to about 5; m is from 2 to about 6, preferably 2 or 3;and L is O, NH, or NR⁴, where R⁴ is an alkyl, preferably an alkyl of 1to about 6 carbon atoms; p is from 1 to 5, preferably 1 or 2, and m+p is2 to 6, preferably about 3. Preferably, R³ is alkylene (includingcycloalkylene), alkylarylene, arylene, or a structure that includes acyanuric ring.

The compound (a)(2) may be prepared by a synthesis that involves a stepof reacting together a compound (a)(2)(A) comprising a carbamate orterminal urea group or a group that can be converted to a carbamate orterminal urea group and also having an isocyanate group and a compound(a)(2)(B) having at least two groups reactive with isocyanatefunctionality. When the compound (a)(2)(A) comprises a group that can beconverted to a carbamate or terminal urea group, the conversion tocarbamate or urea may take place at the same time as the reaction withthe compound having at least two groups reactive with isocyanatefunctionality or after that reaction is completed, to generate thecompound (a)(2).

The second component (b) of the coating composition is a polymer resinthat includes a polyester, a polyurethane, and/or apolyester-polyurethane resin, with the resin or resins used forcomponent (b) comprising active hydrogen-containing functional groupsreactive with the third component (c).

The third component (c) of the coating composition is a curing agentthat is reactive with the first two components.

The invention further provides an article having a substrate, inparticular a flexible substrate, upon which substrate is a cured coatingderived from a coating composition according to the invention and amethod of producing such a coating on a substrate.

DETAILED DESCRIPTION

The composition according to the present invention includes as a firstcomponent (a) a compound having at least one carbamate group or terminalurea group. First, the component (a) may include a compound (a)(1)having at least one carbamate group or terminal urea group and having atleast two linking groups that are urethane or urea. Preferred compounds(a)(1) may be represented by any of the structures: ##STR5## in which R,R', R", R², R³, L, and m are as previously defined; p is from 1 to 5,preferably 1 or 2, and m+p is 2 to 6, preferably about 3. Preferably, R³is alkylene (including cycloalkylene), alkylarylene, arylene, or astructure that includes a cyanuric ring. In one preferred embodiment R³includes a member selected from the group of: ##STR6## and mixturesthereof. L is particularly preferably an oxygen atom.

The compound (a)(1) may be prepared by a step of reacting a mixture thatincludes at least a polyisocyanate (a)(1)(B) and a compound (a)(1)(A)having a carbamate or terminal urea group as defined for the invention,or a group that can be converted to a carbamate or terminal urea group,and also having a group that is reactive with isocyanate functionality.

Compound (a)(1)(A) preferably has a carbamate or terminal urea group,more preferably a carbamate group. The structures for carbamate andterminal urea groups, as those terms are used in connection with thepresent invention, have been set out above. Alternatively, compound(a)(1)(A) may have a group that can be converted to a carbamate orterminal urea group. In the case when compound (a)(1)(A) has a groupthat can be converted to carbamate or terminal urea, the conversion tothe carbamate or terminal urea group is carried out either at the sametime as the reaction involving the polyisocyanate (a)(1)(B) orafterwards to form the compound (a)(1). Groups that can be converted tocarbamate include cyclic carbonate groups, epoxy groups, and unsaturatedbonds. Cyclic carbonate groups can be converted to carbamate groups byreaction with ammonia or a primary amine, which ring-opens the cycliccarbonate to form a β-hydroxy carbamate. Epoxy groups can be convertedto carbamate groups by first converting to a cyclic carbonate group byreaction with CO₂. This can be done at any pressure from atmospheric upto supercritical CO₂ pressures, but is preferably under elevatedpressure (e.g., 60-150 psi). The temperature for this reaction ispreferably 60-150° C. Useful catalysts include any that activate anoxirane ring, such as tertiary amine or quaternary salts (e.g.,tetramethyl ammonium bromide), combinations of complex organotin halidesand alkyl phosphonium halides (e.g., (CH₃)₃ SnI, Bu₄ SnI, Bu₄ PI, and(CH₃)₄ PI), potassium salts (e.g., K₂ CO₃, KI) preferably in combinationwith crown ethers, tin octoate, calcium octoate, and the like. Thecyclic carbonate group can then be converted to a carbamate group asdescribed above. Any unsaturated bond can be converted to a carbamategroup by first reacting with peroxide to convert to an epoxy group, thenwith CO₂ to form a cyclic carbonate, and then with ammonia or a primaryamine to form the carbamate.

Other groups, such as hydroxyl groups or isocyanate groups can also beconverted to carbamate groups. However, if hydroxyl groups were to bepresent on the compound and it is desired to convert those groups tocarbamate after the reaction with the polyisocyanate (a)(1)(B), theywould have to be blocked or protected so that they would not reactduring the reaction with compound (a)(1)(B) or else in stoichiometricexcess so that some would be expected to remain unreacted for laterconversion to the carbamate or terminal urea group(s). Conversion tocarbamate or urea could also be carried out prior to the reaction withcompound (a)(1(A). Hydroxyl groups can be converted to carbamate groupsby reaction with a monoisocyanate (e.g., methyl isocyanate) to form asecondary carbamate group (that is, a carbamate of the structure abovein which R is alkyl) or with cyanic acid (which may be formed in situ bythermal decomposition of urea) to form a primary carbamate group (i.e.,R in the above formula is H). This reaction preferably occurs in thepresence of a catalyst as is known in the art. A hydroxyl group can alsobe reacted with phosgene and then ammonia to form a primary carbamategroup, or by reaction of the hydroxyl with phosgene and then a primaryamine to form a compound having secondary carbamate groups. Anotherapproach is to react an isocyanate with a compound such as hydroxyalkylcarbamate to form a carbamate-capped isocyanate derivative. For example,one isocyanate group on toluene diisocyanate can be reacted withhydroxypropyl carbamate, followed by reaction of the other isocyanategroup with an excess of polyol to form a hydroxy carbamate. Finally,carbamates can be prepared by a transesterification approach wherehydroxyl group is reacted with an alkyl carbamate (e.g., methylcarbamate, ethyl carbamate, butyl carbamate) to form a primary carbamategroup-containing compound. This reaction is performed at elevatedtemperatures, preferably in the presence of a catalyst such as anorganometallic catalyst (e.g., dibutyltin dilaurate). Other techniquesfor preparing carbamates are also known in the art and are described,for example, in P. Adams & F. Baron, "Esters of Carbamic Acid", ChemicalReview, v. 65, 1965.

Groups such as oxazolidone can also be converted to terminal ureagroups. For example, hydroxyethyl oxazolidone can be used to react withthe polyisocyanate (a)(1)(B), followed by reaction of ammonia or aprimary amine with the oxazolidone to generate the terminal ureafunctional group.

In addition to the carbamate or terminal urea group or the group thatcan be converted to a carbamate or terminal urea group, the compound(a)(1)(A) also has a group that is reactive with isocyanatefunctionality. Suitable groups that are reactive with isocyanatefunctionality include, without limitation, hydroxyl groups, primaryamine groups, and secondary amine groups. Preferably, the compound(a)(1)(A) has hydroxyl groups or primary amine groups as the groupsreactive with isocyanate functionality, and more preferably hydroxylgroups. The compound (a)(1)(A) has at least one group that is reactivewith isocyanate functionality, and preferably it has from 1 to about 3of such groups, and more preferably it has one such reactive group. In apreferred embodiment, the compound (a)(1)(A) has a carbamate group and ahydroxyl group. One preferred example of such a compound is ahydroxyalkyl carbamate, particularly a β-hydroxyalkyl carbamate. Inanother preferred embodiment, the compound (a)(1) has a terminal ureagroup and a hydroxyl group.

Suitable compounds (a)(1)(A) include, without limitation, any of thosecompounds having a carbamate or terminal urea group and a hydroxyl orprimary or secondary amine group. Illustrative examples of suitablecompounds of this type include, without limitation, hydroxy alkylcarbamates and hydroxyalkylene alkyl ureas, such as hydroxyethylcarbamate, hydroxypropyl carbamate, and hydroxyethylene ethyl urea.Hydroxypropyl carbamate and hydroxyethyl ethylene urea, for example, arewell known and commercially available. Amino carbamates are described inU.S. Pat. No. 2,842,523. Compounds with hydroxyl and terminal ureagroups may also be prepared by reacting the amine group of an aminoalcohol with hydrochloric acid and then urea to form a hydroxy terminalurea compound. An amino alcohol can be prepared, for example, byreacting an oxazolidone with ammonia. Amino terminal urea compounds canbe prepared, for example, by reacting a ketone with a diamine having oneamine group protected from reaction (e.g., by steric hindrance),followed by reaction with HNCO (e.g., as generated by thermaldecomposition of urea), and finally reaction with water. Alternatively,these compounds can be prepared by starting with a compound having thegroup that can be converted to carbamate or terminal urea, which groupsare described below, and converting that group to the carbamate or ureaprior to beginning the reaction with the polyisocyanate (a)(1)(B).

Other suitable compounds (a)(1)(A) include those compounds (a)(1)(A)having a group reactive with the polyisocyanate (a)(1)(B) and a groupthat can be converted to carbamate such as hydroxyalkyl cycliccarbonates. Certain hydroxyalkyl cyclic carbonates like 3-hydroxypropylcarbonate (i.e., glycerine carbonate) are commercially available. Cycliccarbonate compounds can be synthesized by any of several differentapproaches. One approach involves reacting an epoxy group-containingcompound with CO₂ under conditions and with catalysts as describedhereinabove. Epoxides can also be reacted with β-butyrolactone in thepresence of such catalysts. In another approach, a glycol like glycerineis reacted at temperatures of at least 80° C. with diethyl carbonate inthe presence of a catalyst (e.g., potassium carbonate) to form ahydroxyalkyl carbonate. Alternatively, a functional compound containinga ketal of a 1,2-diol having the structure: ##STR7## can be ring-openedwith water, preferably with a trace amount of acid, to form a1,2-glycol, the glycol then being further reacted with diethyl carbonateto form the cyclic carbonate.

Cyclic carbonates typically have 5- or 6-membered rings, as is known inthe art. Five-membered rings are preferred, due to their ease ofsynthesis and greater degree of commercial availability. Six-memberedrings can be synthesized by reacting phosgene with 1,3-propanediol underconditions known in the art for the formation of cyclic carbonates.Preferred hydroxyalkyl cyclic carbonates used in the practice of theinvention can be represented by the formula: ##STR8## in which R (oreach instance of R if n is more than 1) is a hydroxyalkyl group of 1-18carbon atoms, preferably 1-6 carbon atoms, and more preferably 1-3carbon atoms, which may be linear or branched and may have substituentsin addition to the hydroxyl group, and n is 1 or 2, which may besubstituted by one or more other substituents such as blocked amines orunsaturated groups. The hydroxyl group may be on a primary, secondary,or tertiary carbon. More preferably, R is --(CH₂)_(p) --OH, where thehydroxyl may be on a primary or secondary carbon and p is 1 to 8, andeven more preferably in which the hydroxyl is on a primary carbon and pis 1 or 2.

The second component of the reaction mixture used in forming compound(a)(1) is a polyisocyanate (a)(1)(B). Suitable examples ofpolyisocyanate compounds include both aliphatic polyisocyanates andaromatic polyisocyanates. Useful polyisocyanates include monomericisocyanates, for example aliphatic diisocyanates such as ethylenediisocyanate, 1,2-diisocyanatopropane, 1,3-diisocyanatopropane,1,6-diisocyanatohexane (hexamethylene diisocyanate or HMDI),1,4-butylene diisocyanate, lysine diisocyanate, 1,4-methylenebis-(cyclohexyl isocyanate) and isophorone diisocyanate (IPDI), andaromatic diisocyanates and arylaliphatic diisocyanates such as thevarious isomers of toluene diisocyanate, meta-xylylenediioscyanate andpara-xylylenediisocyanate, 4-chloro-1,3-phenylene diisocyanate,1,5-tetrahydro-naphthalene diisocyanate, 4,4'-dibenzyl diisocyanate, and1,2,4-benzene triisocyanate. In addition, the various isomers ofα,α,α',α'-tetramethyl xylylene diisocyanate can be used.Isocyanate-functional oligomers or low molecular weight reactionproducts of the monomeric isocyanates, which may have from 2 to about 6isocyanate groups, may also be used. Examples of these includeisocyanurates and the reaction products of excess isocyanate withpolyols, such as the product of three moles of diisocyanate with a moleof a triol (e.g., 3 moles of IPDI with one mole of trimethylolpropane ortwo moles of IPDI with one mole of neopentyl glycol); reaction productsof isocyanate with urea (biurets); and reaction products of isocyanatewith urethane (allophanates). The polyisocyanate preferably has two tofour isocyanate groups, and more preferably the polyisocyanate has 2 or3 isocyanate groups per molecule. Isocyanurates such as theisocyanurates of isophorone diisocyanate or hexamethylene diisocyanateare particularly preferred.

In one preferred embodiment, the polyisocyanate (a)(1)(B) is isophoronediisocyanate, the isocyanurate of isophorone diisocyanate, hexamethylenediisocyanate, the isocyanurate of isophorone diisocyanate, or acombination of these. In another preferred embodiment, thepolyisocyanate is an isocyanate-functional monomeric or oligomeric,preferably monomeric, reaction product of a diisocyanate and a polyol.Such a reaction product may prepared by reacting one mole of adiisocyanate per equivalent of polyol. This endcapping is preferablyaccomplished by reacting at least two equivalents of isocyanate of adiisocyanate for each equivalent of hydroxyl of the polyol. Thediisocyanate is preferably isophorone diisocyanate or hexamethylenediisocyanate. The polyol is preferably 2-ethyl-1,6-hexanediol,trimethylolpropane, neopentyl glycol, or a combination of these.

In one preferred embodiment, the compound (a)(1) is produced by a stepthat includes reacting a mixture of an isocyanate (preferably adiisocyanate, e.g., HDI, IPDI, or the isocyanate-functional endcappedpolyol described in the previous paragraph) and a compound such ashydroxypropyl carbamate to form a carbamate-capped polyisocyanatederivative, as described in U.S. Pat. No. 5,512,639.

Compound (a)(1) may also be formed by a reaction mixture includes, inaddition to compounds (a)(1)(A) and (a)(1)(B), a compound (a)(1)(C) thatis an active-hydrogen chain extension agent. Chain extension agents maybe used to increase the length of compound (a)(1) or to bridge togethertwo or more products of the reaction of compounds (a)(1)(A) and(a)(1)(B). Useful active hydrogen-containing chain extension agentsgenerally contain at least two, preferably about two, active hydrogengroups, for example, diols, dithiols, diamines, or compounds having amixture of hydroxyl, thiol, and amine groups, such as alkanolamines,aminoalkyl mercaptans, and hydroxyalkyl mercaptans, among others. Forpurposes of this aspect of the invention, both primary and secondaryamine groups are considered as having one active hydrogen. Activehydrogen-containing chain extension agents also include water. In apreferred embodiment of the invention, a polyol is used as the chainextension agent. In an especially preferred embodiment, a diol is usedas the chain extension agent with little or no higher polyols, so as tominimize branching. Examples of preferred compounds (a)(1)(C) include,without limitation, 1,6-hexanediol, 1,2-hexanediol,2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol,3-hydroxy-2,2-dimethylpropyl 3-hydroxy-2,2-dimethylpropionate (sold byEastman Chemical Co. as Esterdiol 204), 1,4-butanediol, 1,5-pentanediol,neopentyl glycol, cyclohexanedimethanol (sold as CHDM by EastmanChemical Co.), ethyl-propyl-1,5-pentanediol, 2-methyl-2,4-pentanediol,2,2,4-trimethyl-1,3-pentanediol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol,1,3-dihydroxyacetone dimer, 2-butene-1,4-diol, pantothenol,dimethyltartrate, pentaethylene glycol, dimethyl silyl dipropanol, and2,2'-thiodiethanol. While polyhydroxy compounds containing at leastthree hydroxyl groups may be used as chain extenders, the use of thesecompounds may produce higher molecular weight, more branched compounds.Higher-functional polyhydroxy compounds include, for example,trimethylolpropane, trimethylolethane, pentaerythritol, among othercompounds. In a particularly preferred embodiment, the monomericisocyanate is a diisocyanate, especially isophorone or hexamethylenediisocyanate and an average of one of the isocyanate groups per moleculeis reacted with the compound (a)(1)(A) comprising a group that isreactive with isocyanate and a carbamate group or group that can beconverted into a carbamate group, preferably with hydroxypropylcarbamate, and the remaining isocyanate groups are reacted with apolyol, particularly with 2-ethyl-1,6-hexanediol. The reactions of thepolyisocyanate with compounds (a)(1)(A) and (a)(1)(C) can be carried outin any order, including concurrently. While a mixture of reactionproducts may be expected each of the isocyanate groups has about thesame reactivity, at least a part should he the idealized product inwhich a molecule of the polyisocyanate has reacted with both a compound(a)(1)(A) and a compound (a)(1)(C).

Another method of synthesis of compound (a)(1) is to first react theisocyanate groups of a polyisocyanate with a compound having a groupthat is reactive with isocyanate and also a non-isocyanate functionalgroup. This adduct is then reacted with a compound comprising at leastone carbamate group or group that can be converted to carbamate and atleast one group reactive with the non-NCO functional groups. Examples ofnon-isocyanate functional groups include carboxyl, epoxy, hydroxyl,amino. Suitable examples of methods for converting such groups tocarbamate or urea groups have already been described above in detail.

Instead of or in addition to the compound (a)(1), component (a) mayinclude a compound (a)(2) having at least two carbamate and/or terminalurea groups and at least four urethane or urea linking groups. Preferredcompounds (a)(2) may be represented by any of the structures: ##STR9##in which R, R', R", R², L, and m are as previously defined; R⁵ and R⁶are each independently alkylene (including cycloalkylene), preferablyhaving from 1 to about 18 carbon atoms, particularly preferably fromabout 5 to about 12 carbon atoms, alkylarylene, or arylene, or R⁶ is astructure that includes a cyanuric ring, a biuret structure, or anallophonate group.

Compound (a)(2) may be prepared by a step of reacting together acompound (a)(2)(A) comprising a carbamate or terminal urea group or agroup that can be converted to a carbamate or terminal urea group andalso having an isocyanate group and a second compound (a)(2)(B) havingat least two groups reactive with isocyanate functionality.

The compound (a)(2)(A) preferably has, on average, one isocyanate groupper molecule. The compound (a)(2)(A) also preferably has a carbamate orterminal urea group, and particularly preferably has a carbamate group.In one embodiment, (compound (a)(2)(A) is a reaction product of anhydroxyalkyl carbamate and a polyisocyanate compound. In anotherembodiments, compound (a)(2)(A) is a reaction product of an hydroxyalkylcyclic carbonate and a polyisocyanate compound. Preferably, ahydroxyalkyl carbamate and a polyisocyanate are reacted to produce anisocyanate-functional compound with carbamate functionality. In aparticularly preferred embodiment, a β-hydroxyalkyl carbamate is reactedwith one of the isocyanate groups of a diisocyanate, such as IPDI orHMDI, or with one or two of the isocyanate groups of an isocyanurate,such as the isocyanurate of HMDI or IPDI, to produce a compound(a)(2)(A) having both isocyanate and carbamate functionality.

The compound (a)(2)(B) having at least two groups reactive withisocyanate functionality may be a diamine or a polyol, preferably adiol. Particularly preferred compounds (a)(2)(B) having at least twogroups reactive with isocyanate functionality include linear andbranched diols such as 1,6-hexanediol, 2-ethyl-1,6-hexanediol, andneopentyl glycol.

Component (b) of the coating compositions of the invention may be anoligomeric or polymeric resin selected from polyester, polyurethane, orpolyester-polyurethane block copolymer resins. The resin or resinscomprise active hydrogen-containing functional groups that are reactivewith the third component (c) curing agent. Suitable activehydrogen-containing functional groups include, without limitation,hydroxyl functionality, acid functionality, carbamate functionality,terminal urea functionality, and combinations of these. The polymerresin (b) preferably has, on average, at least two reactive-hydrogencontaining functional groups per molecule, although, depending upon thetype of polymer, the average number of functional groups per moleculemay be much higher. The preferred number of functional groups permolecule in a particular case will depend not only upon the type ofpolymer, but also upon the functionality of the crosslinker or curingagent (c), the desired crosslink density, and other factors typicallyconsidered in formulating coating compositions.

In a preferred embodiment, the polymer (b) has carbamate or terminalurea functionality. The carbamate or terminal urea functionality may beintroduced to the polymer by either polymerizing using a carbamate- orterminal urea-functional monomer or by reacting a functional group onthe formed polymer in a further reaction to produce a carbamate orterminal urea functionality at that position. If the functional group onthe polymer (b) is an isocyanate group, the group can be reacted with ahydroxyalkyl carbamate, or with a hydroxy-containing epoxide with theepoxy group subsequently converted to carbamate by reaction with CO₂ andthen ammonia. Preferably, an isocyanate-functional polymer is reactedwith hydroxyethyl carbamate, hydroxypropyl carbamate, hydroxybutylcarbamate, or mixtures thereof. If the functional group is hydroxyl, thereactive group on the carbamate-containing compound may be oxygen of theC(═O)O portion of the carbamate group on an alkyl carbamate or methylol,such as with methylol acrylamide (HO--CH₂ --NH--C(═O)--CH═CH₂). In thecase of the C(═O)O group on an alkyl carbamate, the hydroxyl group onthe polymer undergoes a transesterification with the C(═O)O group,resulting in the carbamate group being appended to the polymer. In thecase of methylol acrylamide, the unsaturated double bond is then reactedwith peroxide, CO₂, and ammonia as described above. If the functionalgroup on the polymer is a carboxyl group, the acid group can be reactedwith epichlorohydrin to form a monoglycidyl ester, which can beconverted to carbamate by reaction with CO₂, and then ammonia.

Carbamate functionality can also be introduced to the polymer ofcomponent (b) by reacting the polymer with a compound that has a groupthat can be converted to a carbamate, and then converting that group tothe carbamate. Examples of suitable compounds with groups that can beconverted to a carbamate include active hydrogen-containing cycliccarbonate compounds (e.g., the reaction product of glycidol and CO₂)that are convertible to carbamate by reaction with ammonia, monoglycidylethers and esters convertible to carbamate by reaction with CO₂ and thenammonia, allyl alcohols where the alcohol group is reactive withisocyanate functionality and the double bond can be converted tocarbamate by reaction with peroxide, and vinyl esters where the estergroup is reactive with isocyanate functionality and the vinyl group canbe converted to carbamate by reaction with peroxide, then CO₂, and thenammonia. Any of the above compounds can be utilized as compoundscontaining carbamate groups rather than groups convertible to carbamateby converting the group to carbamate prior to reaction with the polymer.

Polyesters having epoxide groups or active hydrogen groups such ashydroxyl groups, acid groups, or carbamate groups that are reactive withthe curing agent third component (c) can be used as the polymer (b) inthe composition according to the invention. Such polyesters may beprepared by the polyesterification of organic polycarboxylic acids(e.g., phthalic acid, hexahydrophthalic acid, adipic acid, maleic acid)or their anhydrides with organic polyols (e.g., ethylene glycol,butylene glycol, neopentyl glycol). Hydroxyl or carboxyl functionalpolyesters are prepared by including an excess of the polyol or polyacidmonomer. In a preferred embodiment, the polymer (b) is a polyester resinor polyester-polyurethane copolymer resin having a structural moietyresulting from a ring-opening reaction of a lactone or reaction of ahydroxy acid. Preparation of such resins involves reaction of lactoneand/or hydroxy acid with an active-hydrogen containing monomer orprepolymer. Lactones that can be ring opened by an active hydrogen arewell-known in the art. They include, for example, ε-caprolactone,γ-caprolactone, β-butyrolactone, β-propriolactone, γ-butyrolactone,α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, γ-valerolactone,δ-valerolactone, γ-nonanoic lactone, γ-octanoic lactone, andpentolactone. In one preferred embodiment, the lactone isε-caprolactone. Lactones useful in the practice of the invention canalso be characterized by the formula: ##STR10## wherein n is a positiveinteger of 1 to 7 and R is one or more H atoms, or substituted orunsubstituted alkyl groups of 1-7 carbon atoms.

The lactone ring-opening reaction is typically conducted under elevatedtemperature (e.g., 80-150° C). The reactants are usually liquids so thata solvent is not necessary. However, a solvent may be useful inpromoting good conditions for the reaction even if the reactants areliquid. Any non-reactive solvent may be used, including both polar andnonpolar organic solvents. Examples of useful solvents include toluene,xylene, methyl ethyl ketone, methyl isobutyl ketone, and the like. Acatalyst is preferably present. Useful catalysts include proton acids(e.g., octanoic acid, Amberlyst® 15(Rohm & Haas)), and tin catalysts(e.g., stannous octoate). Alternatively, the reaction can be initiatedby forming a sodium salt of the hydroxyl group on the molecules thatreact will react with the lactone ring.

Useful hydroxy carboxylic acids include dimethylhydroxypropionic acid,hydroxy stearic acid, tartaric acid, lactic acid, 2-hydroxyethyl benzoicacid, and N-(2-hydroxyethyl)ethylene diamine triacetic acid. Thereaction can be conducted under typical esterification conditions, forexample at temperatures from room temperature up to about 150° C., andwith catalysts such as calcium octoate, metal hydroxides like potassiumhydroxide, Group I or Group II metals such as sodium or lithium, metalcarbonates such as potassium carbonate or magnesium carbonate (which maybe enhanced by use in combination with crown ethers), organometallicoxides and esters such as dibutyl tin oxide, stannous octoate, andcalcium octoate, metal alkoxides such as sodium methoxide and aluminumtripropoxide, protic acids like sulfuric acid, or Ph₄ SbI. The reactionmay also be conducted at room temperature with a polymer-supportedcatalyst such as Amerlyst-15® (available from Rohm & Haas) as describedby R. Anand in Synthetic Communications, 24(19), 2743-47 (1994), thedisclosure of which is incorporated herein by reference. The reactionmay be performed with an excess of the compound having the groupreactive with the hydroxy carboxylic acid.

In one preferred embodiment, a polyol, preferably a diol, is extendedwith a lactone, preferably with ε-caprolactone, to form anhydroxyl-functional polyester. In another preferred synthesis, ahydroxy-functional polyester resin is reacted with a lactone orhydroxycarboxylic acid to extend the polyester resin.

Carbamate functionality may be introduced to the polyester by suitablemethods already described. Carbamate-functional polyesters are disclosedin U.S. Pat. Nos. 5,508,379, 5,451,656, and 5,532,061, the disclosuresof each of which is incorporated herein by reference. The polyesterformed from lactone and/or hydroxy acid may similarly have a carbamategroup introduced.

In addition to or instead of the polyester resin, the polymer or resinof component (b) may include a polyurethane having any of the activehydrogen-containing functional groups mentioned above for the polymer(b). Synthesis of polyurethane., particularly hydroxy-functionalpolyurethanes, is well-known in the art. In general, polyurethanes areprepared by reaction of a polyisocyanate component with a polyolcomponent. Preferably, the polyurethane is linear (that is, it isprepared by reacting one or more diisocyanates with one or more diols).Hydroxyl functional polyurethanes may be prepared by reaction an excessof equivalents of diol with diisocyanate(s). Hydroxyl-functional oramine-functional polyurethane, may also be prepared by reacting anisocyanate-terminated polyurethane with an excess of equivalents of adiol, polyol, polyamine, or amino alcohol (such as diethanol amine) in acapping step. Acid-functional polyurethanes may be synthesized byincluding a monomer having acid functionality, such as, withoutlimitation, dimethylolpropionic acid. The hydroxyl groups react to formthe urethane linkages while the acid group remains unreacted in thepolyurethane polymerization. Carbamate- or terminal urea-functionalpolyurethanes can be prepared by reacting an NCO-terminated polyurethanewith a hydroxy carbamate (e.g., hydroxypropyl carbamate) or a hydroxyurea (e.g., hydroxyethyl ethylene urea) using techniques described asabove and in U.S. Pat. No. 5,373,069 or by including a carbamate or ureadiol (which may be formed by ring-opening a hydroxyalkyl cycliccarbonate or a hydroxyalkyl oxazolidone with ammonia or a primaryamine).

Preparation of polyurethanes for coating compositions are described inmany publications. In general, monomeric polyisocyanates such as thosementioned already may be used in preparing the polyurethane. Aliphaticdiisocyanates, particularly IPDI, are preferred. Useful activehydrogen-containing chain extension agents generally contain at leasttwo active hydrogen groups, for example, diols, dithiols, diamines, orcompounds having a mixture of hydroxyl, thiol, and amine groups, such asalkanolamines, aminoalkyl mercaptans, and hydroxyalkyl mercaptans, amongothers. For purposes of this aspect of the invention both primary andsecondary amine groups are considered as having one active hydrogen.Active hydrogen-containing chain extension agents also include water. Ina preferred embodiment of the invention, a polyol is used as the chainextension agent. In an especially preferred embodiment, a diol is usedas the chain extension agent with little or no higher polyols, so as tominimize branching. Examples of preferred diols that are used aspolyurethane chain extenders include, without limitation,1,6-hexanediol, cyclohexanedimethanol (sold as CHDM by Eastman ChemicalCo.), 2-ethyl-1,6-hexanediol, 3-hydroxy-2,2-dimethylpropyl3-hydroxy-2,2-dimethylpropionate (sold by Eastman Chemical Co. asEsterdiol 204), and 1,4-butanediol. While polyhydroxy compoundscontaining at least three hydroxyl groups may be used as chainextenders, the use of these compounds produces branched polyurethaneresins. These higher functional polyhydroxy compounds include, forexample, trimethylolpropane, trimethylolethane, pentaerythritol, amongother compounds. Polymeric chain extension agents can also be used, suchas polyester polyols, polyether polyols, polyurethane polyols, orpolymeric amino group-containing polymers, and it is often preferred toinclude these. Mixtures of any of the above chain extension agents canalso be used. In a preferred embodiment, a polyester polyol is included,in particular a polyester that is the reaction product of caprolactonewith a diol, the polyurethane produced then being apolyester-polyurethane copolymer.

The reaction of the polyisocyanate and chain extension agent isconducted by heating the components in a suitable reaction medium suchas xylene or propylene glycol monoethylether acetate. The use ofcatalysts for this reaction, e.g., organotin catalysts such asdibutyltin diacetate, is well-known in the art. Polyurethanes useful asthe component (b) may have a number average molecular weight of from 600to 6000. Various groups, such as nonionic polyether stabilizing groups,ionic stabilizing groups (e.g., carboxyl groups), unsaturated groups,and the like may be incorporated or appended to the material, as isknown in the art. Active hydrogen or isocyanate terminal groups may beprovided by adjusting the stoichiometry of the chain extension agent andpolyisocyanate in the reaction mixture. A molar ratio of activehydrogen:NCO in the reaction mixture of less than 1 will tend to provideisocyanate-terminated polymers. Other terminal groups may be provided bythe use of capping agents. For example, an acid terminal group can beprovided by capping an isocyanate-terminated polymer with a hydroxyacid.Pendant functional groups may be provided by using chain extensionagents having two active hydrogen groups and the desired functionalgroup, e.g., dimethanol propionic acid, as noted above.

In general, component (b) includes one or more polymers selected frompolyesters, polyurethanes, and polyester-polyurethane copolymers.

As a third component (c), the coating composition includes a curingagent or crosslinker that is reactive with the first two components, (a)and (b). The curing agent has, on average, at least about two functionalgroups reactive with the first and second components. The functionalgroups may be of more than one kind, each kind being reactive with oneor both of the first two components.

Useful curing agents include materials having active methylol ormethylalkoxy groups, such as aminoplast crosslinking agents orphenol/formaldehyde adducts; curing agents that have isocyanate groups,particularly blocked isocyanate curing agents, curing agents that haveepoxide groups, amine groups, acid groups, siloxane groups, cycliccarbonate groups, and anhydride groups; and mixtures thereof. Examplesof preferred curing agent compounds include, without limitation,melamine formaldehyde resin (including monomeric or polymeric melamineresin and partially or fully alkylated melamine resin), blocked orunblocked polyisocyanates (e.g., TDI, MDI, isophorone diisocyanate,hexamethylene diisocyanate, and isocyanurates of these, which may beblocked for example with alcohols or oximes), urea resins (e.g.,methylol ureas such as urea formaldehyde resin, alkoxy ureas such asbutylated urea formaldehyde resin), polyanhydrides (e.g., polysuccinicanhydride), and polysiloxanes (e.g., trimethoxy siloxane). Anothersuitable crosslinking agent is tris(alkoxy carbonylamino) triazine(available from Cytec Industries under the tradename TACT). The curingagent may be combinations of these, particularly combinations thatinclude aminoplast crosslinking agents. Aminoplast resins such asmelamine formaldehyde resins or urea formaldehyde resins are especiallypreferred. Combinations of tris(alkoxy carbonylamino) triazine with amelamine formaldehyde resin and/or a blocked isocyanate curing agent arelikewise suitable and desirable. Component (b) may also contain groupsthat are reactive with the carbamate group of component (a), such as anacrylic polymer containing polymerized isobutoxymethyl acrylamidegroups.

A solvent may optionally be utilized in the coating composition used inthe practice of the present invention. Although the composition usedaccording to the present invention may be utilized, for example, in theform of substantially solid powder, or a dispersion, it is oftendesirable that the composition is in a substantially liquid state, whichcan be accomplished with the use of a solvent. This solvent should actas a solvent with respect to the components of the composition. Ingeneral, the solvent can be any organic solvent and/or water. In onepreferred embodiment, the solvent is a polar organic solvent. Morepreferably, the solvent is selected from polar aliphatic solvents orpolar aromatic solvents. Still more preferably, the solvent is a ketone,ester, acetate, aprotic amide, aprotic sulfoxide, aprotic amine, or acombination of any of these. Examples of useful solvents include,without limitation, methyl ethyl ketone, methyl isobutyl ketone, m-amylacetate, ethylene glycol butyl ether-acetate, propylene glycolmonomethyl ether acetate, xylene, N-methylpyrrolidone, blends ofaromatic hydrocarbons, and mixtures of these. In another preferredembodiment, the solvent is water or a mixture of water with smallamounts of co-solvents.

The coating composition used in the practice of the invention mayinclude a catalyst to enhance the cure reaction. For example, whenaminoplast compounds, especially monomeric melamines, are used as acuring agent, a strong acid catalyst may be utilized to enhance the curereaction. Such catalysts are well-known in the art and include, withoutlimitation, p-toluenesulfonic acid, dinonylnaphthalene disulfonic acid,dodecylbenzenesulfonic acid, phenyl acid phosphate, monobutyl maleate,butyl phosphate, and hydroxy phosphate ester. Strong acid catalysts areoften blocked, e.g. with an amine. Other catalysts that may be useful inthe composition of the invention include Lewis acids, zinc salts, andtin salts.

In a preferred embodiment of the invention, the solvent is present inthe coating composition in an amount of from about 0.01 weight percentto about 99 weight percent, preferably from about 10 weight percent toabout 60 weight percent, and more preferably from about 30 weightpercent to about 50 weight percent.

Coating compositions can be coated on the article by any of a number oftechniques well-known in the art. These include, for example, spraycoating, dip coating, roll coating, curtain coating, and the like. Forautomotive body panels, spray coating is preferred.

Additional agents, for example surfactants, fillers, stabilizers,wetting agents, dispersing agents, adhesion promoters, UV absorbers,hindered amine light stabilizers, etc. may be Incorporated into thecoating composition. While such additives are well-known in the priorart, the amount used must be controlled to avoid adversely affecting thecoating characteristics.

The coating composition according to the invention is preferablyutilized in a high-gloss coating and/or as the clearcoat of a compositecolor-plus-clear coating. High-gloss coatings as used herein arecoatings having a 20° gloss (ASTM D523-89) or a DOI (ASTM E430-91) of atleast 80.

When the coating composition of the invention is used as a high-glosspigmented paint coating, the pigment may be any organic or inorganiccompounds or colored materials, fillers, metallic or other inorganicflake materials such as mica or aluminum flake, and other materials ofkind that the art normally includes in such coatings. Pigments and otherinsoluble particulate compounds such as fillers are usually used in thecomposition in an amount of 1% to 100%, based on the total solid weightof binder components (i.e., a pigment-to-binder ratio of 0.1 to 1).

When the coating composition according to the invention is used as theclearcoat of a composite color-plus-clear coating, the pigmentedbasecoat composition may any of a number of types well-known in the art,and does not require explanation in detail herein. Polymers known in theart to be useful in basecoat compositions include acrylics, vinyls,polyurethanes, polycarbonates, polyesters, alkyds, and polysiloxanes.Preferred polymers include acrylics and polyurethanes. In one preferredembodiment of the invention, the basecoat composition also utilizes acarbamate-functional acrylic polymer. Basecoat polymers may bethermoplastic, but are preferably crosslinkable and comprise one or moretype of crosslinkable functional groups. Such groups include, forexample, hydroxy, isocyanate, amine, epoxy, acrylate, vinyl, silane, andacetoacetate groups. These groups may be masked or blocked in such a wayso that they are unblocked and available for the crosslinking reactionunder the desired curing conditions, generally elevated temperatures.Useful crosslinkable functional groups include hydroxy, epoxy, acid,anhydride, silane, and acetoacetate groups. Preferred crosslinkablefunctional groups include hydroxy functional groups and amino functionalgroups.

Basecoat polymers may be self-crosslinkable, or may require a separatecrosslinking agent that is reactive with the functional groups of thepolymer. When the polymer comprises hydroxy functional groups, forexample, the crosslinking agent may be an aminoplast resin, isocyanateand blocked isocyanates (including isocyanurates), and acid or anhydridefunctional crosslinking agents.

The coating compositions described herein are preferably subjected toconditions so as to cure the coating layers. Although various methods ofcuring may be used, heat-curing is preferred. Generally, heat curing iseffected by exposing the coated article to elevated temperaturesprovided primarily by radiative heat sources. Curing temperatures willvary depending on the particular blocking groups used in thecrosslinking agents, however they generally range between 90° C. and180° C. The first compounds according to the present invention arepreferably reactive even at relatively low cure temperatures. Thus, in apreferred embodiment, the cure temperature is preferably between 115° C.and 150° C., and more preferably at temperatures between 115° C. and140° C. for a blocked acid catalyzed system. For an unblocked acidcatalyzed system, the cure temperature is preferably between 80° C. and100° C. The curing time will vary depending on the particular componentsused, and physical parameters such as the thickness of the layers,however, typical curing times range from 15 to 60 minutes, andpreferably 15-25 minutes for blocked acid catalyzed systems and 10-20minutes for unblocked acid catalyzed systems.

The invention is further described in the following examples. Theexamples are merely illustrative and do not in any way limit the scopeof the invention as described and claimed. All parts are parts by weightunless otherwise noted.

EXAMPLES Preparation 1

A total of 163.4 parts by weight of urethane quality amyl acetate washeated under an inert atomosphere to 60° C. and at that temperature440.83 parts by weight of T-1890 (70% in amyl acetate, available fromCreaNova) and an additional 36.45 parts by weight of amyl acetate wereadded, follwed by 0.15 parts by weight of dibutyltin dilaurate and 12.88parts by weight of amyl acetate. Following these additions, 143.62 partsby weight of hydroxy propyl carbamate were shlowly added. Thetemperature during the addt;ion was kept below 82° C. When the additionof the hydroxy propyl carbamate was complete 17.39 parts by weight ofamyl acetate were added. The reaction mixture was kept at about 80° C.for about 4 hours. After the hold, 6.96 parts by weight of n-butanol,77.0 parts by weight of isobutanol, and 19.0 parts by weight of amylacetate were added. The final resin had a measured nonvolatile contentof 50.9% by weight and a theoretical equivalent weight (based on thecarbamate functionality) of 425.

Example 1

A clearcoat coating composition was prepared by mixing together 98.2grams of the Preparation 1 resin, 75.0 grams of a polyester resin basedon ε-caprolactone (Tone 310, available from Union Carbide), 88.5 gramsof Resimene® 747, 6.4 grams of a UVA solution, 1.3 grams of a hinderedamine light stabilizer, 1.8 grams of a solution of a rheology controlagent, 6.4 grams of a blocked sulfonic acid catalyst (25% active byweight), 32.0 grams of n-butanol, and 53.4 grams of ethylene glycolmonobutyl ether acetate.

Comparative Example A

A clearcoat coating composition was prepared by mixing together 148.3grams of a polyester resin based on ε-caprolactone (Tone 310, availablefrom Union Carbide), 114.8 grams of Resimene® 747, 7.9 grams of a UVAsolution, 1.6 grams of a hindered amine light stabilizer, 2.2 grams of asolution of a rheology control agent, 7.9 grams of a blocked sulfonicacid catalyst (25% active by weight), 39.5 grams of n-butanol, and 52.6grams of ethylene glycol monobutyl ether acetate.

Testing of Coating Compositions

Primed plastic panels were coated with a black basecoat and then theclearcoat composition wet-on-wet. The coated panels were cured afterapplication of the clearcoat composition by baking at 120° C. for 30minutes in a gas-fired oven. The cured clear coat films were 1.5-2.0mils thick.

The coated panels were subjected to outdoor exposure testing in aJacksonville, Fla. environmental etch testing program. The amount ofenvironmental etch was rated on a scale of 1 to 10D, with 1 being no orlittle film damage up to 10 being severe film damage and 10A, 10B, 10C,and 10D being increasingly severe film damage.

    ______________________________________                                        Clearcoat                 Exposure Time                                       Composition     Etch Rating                                                                             (weeks)                                             ______________________________________                                        Example 1        6        7                                                   Comparative Ex. A                                                                             10D       7                                                   ______________________________________                                    

The invention has been described in detail with reference to preferredembodiments thereof. It should be understood, however, that variationsand modifications can be made within the spirit and scope of theinvention.

What is claimed is:
 1. A curable coating composition, comprising:(a) acomponent selected from the group consisting of:(1) a compound having atleast one carbamate group or urea group that is prepared by a step ofreacting a mixture comprising:(A) a compound comprising a carbamate orurea group or a group that can be converted to a carbamate or urea groupand a group that is reactive with (a)(1)(B) and (B) a polyisocyanate,(2) a compound having at least one carbamate group or urea group that isprepared by a step of reacting a mixture comprising:(A) a compoundcomprising a carbamate or urea group or a group that can be converted toa carbamate or urea group and an isocyanate group and (B) a compoundhaving at least two groups reactive with isocyanate functionality, andmixtures thereof; (b) a polyester, polyurethane, orpolyester-polyurethane copolymer comprising active hydrogen-containingfunctional groups that are reactive with component (c), and (c) a curingagent that is reactive with compound (a) and compound (b), wherein saidcarbamate group has a structure: ##STR11## in which R is H or alkyl, andfurther wherein said urea group has a structure: ##STR12## in which R'and R" are each independently H or alkyl, or R' and R" together form aheterocyclic ring structure.
 2. A composition according to claim 1,wherein component (a) has at least one carbamate group.
 3. A compositionaccording to claim 1, wherein component (a) comprises compound (a)(1).4. A composition according to claim 3, wherein component (a)(1)comprises at least one carbamate group.
 5. A composition according toclaim 3, wherein compound (a)(1)(A) is monomeric.
 6. A compositionaccording to claim 3, wherein compound (a)(1)(A) has a group selectedfrom the group consisting of carbamate groups, urea groups, andcombinations thereof.
 7. A composition according to claim 3, whereincompound (a)(1)(A) has a carbamate group.
 8. A composition according toclaim 3, wherein compound (a)(1)(A) is a hydroxyalkyl carbamate.
 9. Acomposition according to claim 3, wherein compound (a)(1)(A) is ahydroxyalkyl cyclic carbonate.
 10. A composition according to claim 3,wherein the group on compound (a)(1)(A) that is reactive with (a)(1)(B)is hydroxyl or amino.
 11. A composition according to claim 3, whereincompound (a)(1)(A) has one group that is reactive with (a)(1)(B).
 12. Acomposition according to claim 3, wherein compound (a)(1)(B) ismonomeric.
 13. A composition according to claim 3, wherein compound(a)(1)(B) is an isocyanurate.
 14. A composition according to claim 3,wherein compound (a)(1)(B) is a monomeric, isocyanate-functionalreaction product of a diisocyanate and a polyol.
 15. A compositionaccording to claim 1, wherein component (a) comprises compound (a)(2).16. A composition according to claim 15, wherein compound (a)(2)(A) has,on average, one isocyanate group per molecule.
 17. A compositionaccording to claim 15, wherein compound (a)(2)(A) has a carbamate orurea group.
 18. A composition according to claim 15, wherein compound(a)(2)(A) has a carbamate group.
 19. A composition according to claim15, wherein compound (a)(2)(A) is a reaction product of an hydroxyalkylcarbamate and a monomeric isocyanate compound.
 20. A compositionaccording to claim 15, wherein compound (a)(2)(A) is a reaction productof an hydroxyalkyl cyclic carbonate and a monomeric isocyanate compound.21. A composition according to claim 15, wherein compound (a)(2)(B) is adiamine.
 22. A composition according to claim 15, wherein compound(a)(2)(B) is a polyol.
 23. A composition according to claim 15, whereincompound (a)(2)(B) is a diol.
 24. A composition according to claim 1,wherein component (b) is a polyester resin or a polyester-polyurethanecopolymer resin having a structural moiety resulting from a ring-openingreaction of a lactone.
 25. A composition according to claim 1, whereincomponent (b) has functionality selected from the group consisting ofcarbamate functionality, urea functionality, hydroxyl functionality, andcombinations thereof.
 26. A composition according to claim 1, whereincomponent (b) has functionality selected from the group consisting ofcarbamate functionality, hydroxyl functionality, and combinationsthereof.
 27. A composition according to claim 1, wherein component (b)has carbamate functionality.
 28. A composition according to claim 1,wherein component (c) is an aminoplast.
 29. A composition according toclaim 1, wherein component (c) is a melamine formaldehyde resin.
 30. Acomposition according to claim 1, wherein component (c) is a ureaformaldehyde resin.
 31. A composition according to claim 1, wherein Rand R" are each independently H or alkyl of from 1 to about 4 carbonatoms.
 32. A composition according to claim 1, wherein R and R" are eachH.
 33. A composition according to claim 1, wherein the composition is aclearcoat coating composition.
 34. A composition according to claim 1,further comprising a pigment.
 35. An article comprising a substratehaving thereon a cured coating derived from a coating compositionaccording to claim
 1. 36. An article according to claim 35, wherein saidsubstrate is a flexible substrate.
 37. A curable coating composition,comprising:(a) a compound selected from the group consisting ofcompounds having structures: ##STR13## and mixtures thereof; and (b) apolyester, polyurethane, or polyester-polyurethane copolymer comprisingactive hydrogen-containing functional groups that are reactive withcomponent (c), and (c) a curing agent that is reactive with compound (a)and component (b),wherein R is H or alkyl; R' and R" are eachindependently H or alkyl, or R' and R" together form a heterocyclic ringstructure; R² is alkylene or substituted alkylene; R¹, R³, R⁵, and R⁶are independently alkylene, cycloalkylene, or arylalkylene, or R³, R⁵,and R⁶ are independently arylene, or a structure that includes acyanuric ring, a urethane group, a urea group, a carbodiimide group, abiuret structure, or an allophonate group; n is from 0 to about 10; m isfrom 2 to about 6; and L is O, NH, or NR⁴, where R⁴ is an alkyl; inwhich p is from 1 to 5, and m+p is 2 to 6; in which R⁵ and R⁶ are eachindependently alkylene, cycloalkylene, alkylarylene, or arylene, or R⁶is a structure that includes a cyanuric ring, a biuret structure, or anallophonate group.